The present invention relates generally to methods and apparatus for spooling a linear flexible member. More particularly, the present invention relates to methods and apparatus for guiding a flexible member onto a rotating drum.
A spooler is a device used to guide a flexible member onto a drum and are used in many industries. Examples of flexible members include: cable, wireline, slickline, sandline, wire rope, and wire. Overhead spoolers comprise a swiveling arm mounted above a drum with a guide roller device or measuring head on the end to guide the flexible member onto the drum to ensure even and smooth wraps. The opposite end of the arm is attached to one or more swivel joints that allow the arm to be controlled in position both side to side and up and down. Many spoolers rely on hydraulic, or other power, to control the position of the arm.
In many spooling applications, it is desirable for the spooler to allow the material to “free spool” from side-to-side but provide power to guide the material onto the drum as needed. Many spooled materials have very little pulling power from side-to-side while wrapping onto the drum and too much drag from the spooler arm will not allow the material to self-spool. Thus, it is often necessary for the operator to constantly power the spooler arm in order to keep the spooler head properly positioned.
Because of this constant operation, auto-spoolers have been developed that move in synchronization with the drum to constantly move side-to-side as the drum rotates. When utilized in spooling multi-strand wireline cable, these auto-spoolers often do not operate properly. The multi-stranded cable has a tendency to change diameter as the cable is torqued and twisted. Although the diameter changes are minimal they can have a large effect on how the cable is spooled onto a drum. For example, consider a cable with a nominal outer diameter of 0.220 inches that sees a maximum diameter variation of 0.002 inches. If the cable is being wound on a 30 inch wide drum, the drum will hold 136 wraps per row at the nominal diameter, 135 wraps per row at the maximum diameter of 0.222 inches, and 137 wraps per row at the minimum diameter of 0.218 inches. Because each row of cable uses the previously spooled row as a guide, if the number of wraps per row is not consistent, the potential of damage to the cable exists.
Thus, there remains a need to develop methods and apparatus for spooling flexible materials onto a drum, which overcome some of the foregoing difficulties while providing more advantageous overall results.